Skyrmion and chiral bobber solitons for racetrack storage

Read an article this week in Science Daily (Magnetic skyrmions: Not the only one of their class; …) about new magnetic structures that could lend themselves to creating a new type of moving, non-volatile storage.  (There’s more information in the press release and the Nature paper [DOI: 10.1038/s41565-018-0093-3], behind a paywall).

Skyrmions and chiral bobbers are both considered magnetic solitons, types of magnetic structures only 10’s of nm wide, that can move around, in sort of a race track configuration.

Delay line memories

Early in computing history, there was a type of memory called a delay line memory which used various mechanisms (mercury, magneto-resistence, capacitors, etc.) arranged along a circular line such as a wire, and had moving pulses of memory that raced around it. .

One problem with delay line memory was that it was accessed sequentially rather than core which could be accessed randomly. When using delay lines to change a bit, one had to wait until the bit came under the read/write head . It usually took microseconds for a bit to rotate around the memory line and delay line memories had a capacity of a few thousand bits 256-512 bytes per line,  in today’s vernacular.

Delay lines predate computers and had been used for decades to delay any electronic or acoustic signal before retransmission.

A new racetrack

Solitons are being investigated to be used in a new form of delay line memory, called racetrack memory. Skyrmions had been discovered a while ago but the existence of chiral bobbers was only theoretical until researchers discovered them in their lab.

Previously, the thought was that one would encode digital data with only skyrmions and spaces. But the discovery of chiral bobbers and the fact that they can co-exist with skyrmions, means that chiral bobbers and skyrmions can be used together in a racetrack fashion to record digital data.  And the fact that both can move or migrate through a material makes them ideal for racetrack storage.

Unclear whether chiral bobbers and skyrmions only have two states or more but the more the merrier for storage. I am assuming that bit density or reliability is increased by having chiral bobbers in the chain rather than spaces.

Unlike disk devices with both rotating media and moving read-write heads, the motion of skyrmion-chiral bobber racetrack storage is controlled by a very weak pulse of current and requires no moving/mechanical parts prone to wear/tear. Moreover, as a solid state devices, racetrack memory is not sensitive to induced/organic vibration or shock,  So, theoretically these devices should have higher reliability than disk devices.

There was no information comparing the new racetrack memory reliability to NAND or 3D Crosspoint/PCM SSDs, but there may be some advantage here as well. I suppose one would need to understand how to miniaturize the read-erase-write head to the right form factor for nm racetracks to understand how it compares.

And I didn’t see anything describing how long it takes to rotate through bits on a skyrmion-chiral bobber racetrack. Of course, this would depend on the number of bits on a racetrack, but some indication of how long it takes one bit to move, one postition on the racetrack would be helpful to see what its rotational latency might be.


At the moment, reading and writing skyrmions and the newly discovered chiral bobbers takes a lot of advanced equipment and is only done in major labs. As such, I don’t see a skyrmion-chiral bobber racetrack storage device arriving on my desktop anytime soon. But the fact that there’s a long way to go before, we run out of magnetic storage options, even if it is on a chip rather than magnetic media,  is comforting to know. Even if we don’t ever come up with an economical way to produce it.

I wonder if you could synchronize rotational timing across a number of racetrack devices, at least that way you could be reading/erasing/writing a whole byte, word, double word etc, at a time, rather than a single bit.


Photo Credit(s): From Experimental observation of chiral magnetic bobbers in B20 Type FeGe paper

From Experimental observation of chiral magnetic bobbers in B20 Type FeGe paper

From Timeline of computer history Magnetoresistive delay lines

From Experimental observation of chiral magnetic bobbers in B20 Type FeGe paper

Hitachi Vantara HCP, hits it out of the park #datacenternext

We talked with Hitachi Vantara this past week at a special Tech Field Day extra event (see videos here). This was an all day affair and was a broad discussion of Hitachi’s infrastructure portfolio.

There was much of interest in the days session but one in particular caught my eye and that was the session on Hitachi Vantara’s Content Platform (HCP).

Hitachi has a number of offerings surrounding their content platform, including:

  • HCP, on premises object store:
  • HCP Anywhere, enterprise file synch and share using HCP,
  • HCP Content Intelligence, compliance and content search for HCP object storage, and
  • HCP Data Investor, file gateway to HCP object storage.

I already knew about these  offerings but had no idea how successful HCP has been over the years. According to Hitachi Vantara, HCP has over 4000 installations worldwide with over 2000 customers and is currently the number 1 on premises, object storage solution in the world.

For instance, HCP is installed in 4 out of the 5 largest banks, insurance companies, and TelCos worldwide. HCP Anywhere has over a million users with over 15K in Hitachi alone.  Hitachi Vantara has some customers using HCP installations that support 4000-5000 object ingests/sec.

HCP software supports geographically disbursed erasure coding, data compression, deduplication, and encryption of customer object data.

HCP development team has transitioned to using micro services/container based applications and have developed their Foundry Framework to make this easier. I believe the intent is to ultimately redevelop all HCP solutions using Foundry.

Hitachi mentioned a couple of customers:

  • US Government National Archives which uses HCP behind Pentaho to preserve presidential data and metadata for 100 years, and uses all open APIs to do so
  • UK Rabo Bank which uses HCP to support compliance monitoring across a number of data feeds
  • US  Ground Support which uses Pentaho, HCP, HCP Content Intelligence and HCP Anywhere  to support geospatial search to ascertain boats at sea and what they are doing/shipping.

There’s a lot more to HCP and Hitachi Vantara than summarized here and I would suggest viewing the TFD videos and check out the link above for more information.


Want to learn more, see these other TFD bloggers posts:

Hitachi is reshaping its IT division by Andrew Mauro (@Andrew_Mauro)

MIT’s new Navion chip for better Nano drone navigation

Read an article this week in Science Daily (Chip upgrade help’s bee-sized drones navigate) about a recent chip created by MIT, called Navion, that reduces size and power consumption for electronics used in drone navigation. The chip is also documented on MIT’s Navion project homepage and in a technical  paper describing the new VIO (Visual-Inertial Odometry ) Navion chip.

The Navion chip can perform inertial measurement at 52Khz as well as process video streams of 752×480 stereo images at 171 frames per second in a 20 sqmm package consuming only 24mW of power. The chip was fabricated on a 65nm CMOS process line.

Navion is the result of a collaborative design process which optimized electronics required to perform  drone navigation processing. By placing all the memory required for inertial measurement and image analysis and all the processing hardware on the same chip, they have substantially reduced power consumption and space requirements for drone navigation.

Navion architecture

Navion uses a state of the art, non-linear factor graph optimization algorithm to navigate in space.  It doesn’t sound like  DL neural net image recognition but more like a statistical/probabilistic approach to image mapping and place estimation. The chip uses image compression, two stage memory, and sparse linear solver memory to reduce image processing memory requirements from 3.5MB to less than 1MB.

The chip uses 3 inputs: two images (right &  left image) and IMU (inertial management unit sensor) and has one (complex output), its estimate of the current state of where it is on the map.

Navion processing creates and maintains a 3D map using stereo images and provides navigational support to move through that space.  According to the paper, the Navion chip updates the state(s) and sparse 3D map at a KF (Kalman filter) rate of between 16 and 90 fps. Navion also offers configurations options to maximize accuracy, throughput or energy efficiency.

Navion compares well to other navigation electronics

The table shows comparisons of the Navion chip against other traditional navigational systems that use Xeon, ARM or FPGA chips. As far as I can tell it’s either much better or at least on a par with these other larger, more complex, power hungry systems.

Nano drones are coming to our space, sooner than anyone expects.


Photo credit(s): System overview from Navion project page (c) 2018 MIT;

Picture of chip with layout  from Navion project page (c) 2018 MIT;

Navion: A Fully Integrated Energy-Efficient Visual-Inertial Odometry Accelerator for Autonomous Navigation of Nano Drones (c) 2018 MIT

NetApp’s new NVMeoF/FC AFF & Cloud Data Volumes for every cloud

We attended a NetApp analyst event in their CA HQ last week and they had some interesting announcements as well other information to share. 1st up new faster ONTAP storage.


NetApp announced this week that their latest generation AFF (All Flash FAS) systems will support FC NVMeoF. We asked if this was just for NVMe SSDs or did it apply to all AFF media. The answer was it’s just another host interface which the customer can license for NVMe SSDs (available only on AFF F800) or SAS SSDs (A700S, A700, and A300). The only AFF not supporting the new host interface is their lowend AFF A220.

As for which NVMeoF, they only support FC at the moment, and it’s our belief that the FC NVMeoF spec is most well defined these days and the FC switch hardware (Brocade-Broadcom since Gen 5, now shipping Gen 6, Cisco not sure) already has NVMeoF support.

NetApp also mentioned support for 100GbE (A800 & A700S only) and 32Gbs FC hardware (all AFF systems but A220). So, presumably they offer NVMeoF for both 32Gbps and 16Gbps FC.

No word on when this will be available for Ethernet FCoE or iSCSI (iNVMe?) but with all the major storage vendors bar one, moving to NVMe SSDs it’s only a matter of time before they also support Ethernet NVMeoF.

As for AFF NVMeoF performance, the answer wasn’t entirely satisfactory. The indication was that the interface reduced response time by 10 usecs or so for NVMe SSDs over SAS SSDs. But I didn’t see any other performance information to substantiate that.

We did see on their AFF datasheet that with NVMe SSDs and NVMeoF FC, the AFF A800 response time was sub 200usec with throughput of 300GB/s (in a 24 node cluster, 12 HA pairs). This means they add only about 100usec for ONTAP data services, a decent trade off from our perspective. Later in their datasheet they say the A800 is capable of 1.3M IOPS and sub-500usec latencies. Unsure why they quoted both numbers.

Cloud Data Volumes

NetApp is taking storage to the cloud. They just announced that NetApp Cloud Data Volumes will be available as a native service under Google Cloud Platform (GCP). NetApp Cloud Data Volume is a storage-as-a-service offering that provides on demand ONTAP file services in the cloud.

For GCP,  both Google and NetApp will be offering the service. Dianne Green, GCP VP said Cloud Data Volumes are a bit like Kubernetes, disruption without disrupting. Customers can easily migrate their onprem file based applications to the cloud without having to worry about the performance of their data or data protection for that matter.

Getting the data there is another matter, but NetApp has other services like CloudSync and someday (maybe for Cloud Data Volumes), SnapMirror, which can help customers move data to and from the cloud.

Currently Cloud Data Volumes are in public preview as an Microsoft Azure Enterprise NFS (and SMB) service. It’s also in beta (I think) in AWS marketplace. And availability on GCP is still restricted. There’s a lot of emphasis at NetApp events on Cloud Data Volumes given its current status on public cloud providers but we think they are trying to gain some experience before they roll it out to the rest of the world.

However,  Jean English, NetApp CMO mentioned that NetApp’s Cloud Data Service business unit has over 1800 customers and currently supports a multi-PB storage footprint in various clouds. Note, this is not just Cloud Data Volumes but comprises all NetApp Cloud Data Services, which includes ONTAP Cloud, NPS, CloudSync, AltaVault, etc. Nonetheless, it’s an impressive indicator of just how far they have come in applying their storage magic to the public cloud in a short time. The hyperscalers (read public cloud providers) say NetApp is 2 or more years ahead of all the other competition and from what we can see, it’s true.

One of the key differentiators between NetApp Cloud Data Volumes and ONTAP Cloud is performance SLAs. Cloud Data Volume customers can select and purchase a specified performance SLA. We believe it comes at three levels and is normally purchased on a pay as you go, consumption based, service offering. However, it’s also available to be billed periodically, other purchase options may be available as well.

When asked what storage was behind the service, the only thing NetApp would confirm was that it was ONTAP storage, present in public cloud data centers in various regions. So Cloud Data Volumes is available in only specific regions but I would expect that to expand over time.

Data Visualization Center

They also christened their new Data Visualization Center (DVC) and we had a multi-course meal at the Bistro at the center. The DVC had a wrap around, 1.5 floor tall screen which showed some of NetApp customer success stories. Inside the screen was a more immersive setting and there was plenty of VR equipment in work spaces alongside customer conference rooms.

Full Disclosure: NetApp paid for all our travel, hotel and food during the analyst event and gave us all Google Home Minis as going away presents and NetApp is a long time customer of my firm.

Western Digital at SFD15: ActiveScale object storage

Phill Bullinger and his staff from Western Digital presented at Storage Field Day 15 (SFD15) on a number of their enterprise products including Tegile and IntelliFlash but the one that caught my interest was their ActiveScale object store acquired from Amplidata back in 2015.

ActiveScale is an onprem, object storage system that provides cloud-like  economics for customer data.

ActiveScale Hardware

ActiveScale systems can both scale up and scale out within a single site. ActiveScale systems have both  storage and system nodes. Storage nodes perform erasure coding and System nodes are control points and metadata managers for the object store.

ActiveScale comes in two appliance configurations that contain both storage and system nodes and storage required.  The two appliances are:

  • ActiveScale P100 is a 7U 720TB pod system and A full rack of P100s can read 8GB/sec and can have 17-9s data availability. The P100 can scale up to 2.1PB in a single rack and up to 18PB in the same namespace. The P100 is a higher performing solution with better performing storage and system nodes
  • ActiveScale X100 is a 42U rack scale solution that holds up to 588 12TB drives or 5.8PB per rack. The X100 can scale up to 9 racks or 52PB in the same namespace. The X100 is a denser configuration with only 6 storage nodes and as such, has a better $/GB than the P100 above.

As WDC is both the supplier of the ActiveScale appliance and a supplier of disk storage they can be fairly aggressive with pricing on appliance systems.

Data integrity in ActiveScale

They make a point of saying that ActiveScale object metadata and data are stored separately. By separating data and metadata, they claim to be  more resilient to system failures. Object metadata is 3 way replicated, in a replicated database, residing in system nodes. Other object systems often store metadata and object data in the same way.

Object data can be erasure coded. That is, object data is chunked, erasure coding protected and then spread across multiple disk drives for data protection. ActiveScale erasure coding is called BitSpread. With BitSpread customers identify the number of disk drives to spread object data across and the number of drive failures the system should recover from without data loss.

A typical BitSpread configuration splits object data into 18 chunks and spreads these chunks across storage columns. A storage column is from 6-18 storage nodes. There’s no pre-allocated space in BitSpread. Object data chunks are allocated to disk storage based on current capacity and performance of the system, within redundancy constraints.

In addition, ActiveScale has a background task called BitDynamics that scans  erasure coded chunks and does a mathematical health check on the object data. If a chunk is bad, the object data chunk can be recovered and re-erasure coded back to proper health.

WDC performance testing shows that BitDynamics has 0 performance degradation when performing re-erasure coding. Indeed, they took out 98 drives in an ActiveScale cluster and BitDynamics re-coded all that data onto other disk drives and detected no performance impact. No indication how long  re-encoding 98 disk drives of data took nor the % of object store capacity utilization at the time of the test but presumably there’s a report someplace to back this up

Unlike many public cloud based object storage systems, ActiveScale is strongly consistent. That is object puts (writes) are not responded back to the entity doing the put,  until the object metadata and object data are properly and safely recorded in the object store.

ActiveScale also supports 3 site erasure coding. GeoSpread is their approach to erasure coding across sites. In this case, object metadata is replicated across 3 system nodes across the sites. Object data and erasure coded information is split into 20 chunks which are then spread across the three sites.  This way if any one site goes down, the other two sites have sufficient metadata, object data chunks and erasure coded information to reconstruct the data.

ActiveScale 5.2 now supports asynch replication. That is any one ActiveScale cluster can replicate to any other ActiveScale cluster located continent distances away.

Unclear how GeoSpread and asynch replication would interact together, but my guess is that each of the 3 GeoSpread sites could be asynchronously replicated to 3 other sites for maximum redundancy.

Both GeoSpread and ActiveScale replication impact performance,  depending on how far the sites are from one another and the speed and bandwidth of the links between sites.

ActiveScale markets

ActiveScale’s biggest market is media and entertainment (M&E), mostly used for media archive or tape replacement/augmentation. WDC showed one customer case study for the Montreaux Jazz Festival, which migrated 49 years of performance videos up to ActiveScale and can now stream any performance, on request, without delay. Montreax media is GeoSpread across 3 sites in France. Another option is to perform transcoding on the object media in realtime and stream the transcoded media.

Another large market is Bio/Life Sciences. Medical & biological scanners are transitioning to higher resolution scans which take more data space. And this sort of medical information needs to be kept a long time

Data analytics on ActiveScale

One other emerging market is data analytics. With the new S3A (S3 adapter), Hadoop clusters can now support object storage as a 2nd tier. One problem with data analytics is that they have lots of data and storing it in triplicate, costs an awful lot.

In big data world, datasets can get very large very quickly. Indeed PB sizes data sets aren’t that unusual. And with triple replication (in native HDFS). When HDFS runs out of space you have to delete data. Before S3A, the only way you could increase storage you had to scale out (with compute and storage and networking) in order to add capacity.

Using Hadoop’s S3A, ActiveScale’s can provide cold archive for data analytics.  From a Hadoop user/application perspective, S3A ActiveScale storage looks like just another directory under HDFS (Hadoop Data File System). You can run MapReduce or other Hadoop application directly against object buckets. But a more realistic approach is to move inactive or cold data from an disk resident HDFS directory to a S3A directory

HDFS and MapReduce are tightly coupled and were designed to have data close to where computation happens. So,  as long as the active data or working set data is on HDFS disk storage or directly in memory the rest of the (inactive) data could all be placed on S3A object storage. Inactive data is normally historical data no longer being actively analyzed while newer data would be actively analyzed. Older, inactive data can be manually or automatically archived off to S3A. With HIVE you can partition your database to have active data in HDFS disk storage and inactive data in S3A.

Another approach is if the active, working set data can all fit directly in memory then the data can reside on S3A object storage. This way the data is read from S3A storage into memory, analyzed there and output be done back to object store or HDFS disk. Because the data is only read (loaded) once, there’s only a minimal performance penalty to use S3A storage.

Western Digital is an active contributor to Hadoop S3A and have recently added performance improvements to S3A, such as better caching, partial object reading, and core XML performance tuning options.

If your interested in learning more about Western Digital ActiveScale, check out the videos referenced earlier and their website.

Also you may be interested in these other posts on the WD sessions at SFD15:

The A is for Active, The S is for Scale by Dan Firth (@PenguinPunk)


A new way to compute

I read an article the other day on using using random pulses rather than digital numbers to compute with, see Computing with random pulses promises to simplify circuitry and save power, in IEEE Spectrum. Essentially they encode a number as a probability in a random string of bits and then use simple logic to compute with. This approach was invented in the early days of digital logic and was called stochastic computing.

Stochastic numbers?

It’s pretty easy to understand how such logic can work for fractions. For example to represent 1/4, you would construct a bit stream that had one out of every four bits, on average, as a 1 and the rest 0’s. This could easily be a random string of bits which have an average of 1 out of every 4 bits as a one.

A nice result of such a numerical representation is that it easily results in more precision as you increase the length of the bit stream. The paper calls this progressive precision.

Progressive precision helps stochastic computing be more fault tolerant than standard digital logic. That is, if the string has one bit changed it’s not going to make that much of a difference from the original string and computing with an erroneous number like this will probably result in similar results to the correct number.  To have anything like this in digital computation requires parity bits, ECC, CRC and other error correction mechanisms and the logic required to implement these is extensive.

Stochastic computing

2 bit multiplier

Another advantage of stochastic computation and using a probability  rather than binary (or decimal) digital representation, is that most arithmetic functions are much simpler to implement.


They discuss two examples in the original paper:

  • AND gate

    Multiplication – Multiplying two probabilistic bit streams together is as simple as ANDing the two strings.

  • 2 input stream multiplexer

    Addition – Adding two probabilistic bit strings together just requires a multiplexer, but you end up with a bit string that is the sum of the two divided by two.

What about other numbers?

I see a couple of problems with stochastic computing:,

  • How do you represent  an irrational number, such as the square root of 2;
  • How do you represent integers or for that matter any value greater than 1.0 in a probabilistic bit stream; and
  • How do you represent negative values in a bit stream.

I suppose irrational numbers could be represented by taking a near-by, close approximation of the irrational number. For instance, using 1.4 for the square root of two, or 1.41, or 1.414, …. And this way you could get whatever (progressive) precision that was needed.

As for integers greater than 1.0, perhaps they could use a floating point representation, with two defined bit strings, one representing the mantissa (fractional part) and the other an exponent. We would assume that the exponent rather than being a probability from 0..1.0, would be inverted and represent 1.0…∞.

Negative numbers are a different problem. One way to supply negative numbers is to use something akin to complemetary representation. For example, rather than the probabilistic bit stream representing 0.0 to 1.0 have it represent -0.5 to 0.5. Then progressive precision would work for negative numbers as well a positive numbers.

One major downside to stochastic numbers and computation is that high precision arithmetic is very difficult to achieve.  To perform 32 bit precision arithmetic would require a bit streams that were  2³² bits long. 64 bit precision would require streams that were  2**64th bits long.

Good uses for stochastic computing

One advantage of simplified logic used in stochastic computing is it needs a lot less power to compute. One example in the paper they use for stochastic computers is as a retinal sensor for in the body visual augmentation. They developed a neural net that did edge detection that used a stochastic front end to simplify the logic and cut down on power requirements.

Other areas where stochastic computing might help is for IoT applications. There’s been a lot of interest in IoT sensors being embedded in streets, parking lots, buildings, bridges, trucks, cars etc. Most have a need to perform a modest amount of edge computing and then send information up to the cloud or some edge consolidator intermediate

Many of these embedded devices lack access to power, so they will need to make do with whatever they can find.  One approach is to siphon power from ambient radio (see this  Electricity harvesting… article), temperature differences (see this MIT … power from daily temperature swings article), footsteps (see Pavegen) or other mechanisms.

The other use for stochastic computing is to mimic the brain. It appears that the brain encodes information in pulses of electric potential. Computation in the brain happens across exhibitory and inhibitory circuits that all seem to interact together.  Stochastic computing might be an effective way, low power way to simulate the brain at a much finer granularity than what’s available today using standard digital computation.


Not sure it’s all there yet, but there’s definitely some advantages to stochastic computing. I could see it being especially useful for in body sensors and many IoT devices.


Photo Credit(s):  The logic of random pulses

2 bit by 2 bit multiplier, By Sodaboy1138 (talk) (Uploads) – Own work, CC BY-SA 3.0, wikimedia

AND ANSI Labelled, By Inductiveload – Own work, Public Domain, wikimedia

2 Input multiplexor

A battery free implantable neural sensor, MIT Technology Review article

Integrating neural signal and embedded system for controlling a small motor, an IntechOpen article